Heightened awareness of the consequences of poor practice in the disposal and storage of waste materials has led to governmental regulations requiring improved waste management systems. As a result, systems using a combination of synthetic flexible membrane liners and clay layers and incorporating leachate detection and collection procedures have been designed to meet stringent standards. However, such systems are relatively expensive and difficult to construct, particularly for large storage areas. As a consequence, most liners for non-hazardous waste are constructed of clay, it having been assumed from laboratory tests that if clay were compacted to a reasonably high density in a liner, it would be impermeable to water. Unfortunately, it has been found from field trials that typical clay clods or clumps are often not broken down to as small particles as in laboratory tests. Consequently, water passing through field compacted clay tends to flow around and between soil clods in much same way as if the clods were mineral aggregate particles. Furthermore, during full-scale construction operations in the field under varying soil, terrain, and weather conditions, it is very difficult to achieve the uniformity of mixing and compaction required for waste storage liners. The overall result is that, generally, field clay liners turn out to be significantly more permeable than initially predicted from laboratory tests.
A further problem with the current system is the installation and maintenance of the synthetic membrane (geomembrane) placed on top of the clay layer. For large areas, seams or joints need to be welded or glued watertight. The membranes are easily punctured by construction equipment or large animals and they are difficult to maintain watertight. In addition, they are very expensive to construct because of the hand-labor required.